The present invention relates to electrical resistance strain gages of the type employed for measuring strains where it is desired to have a high output or gage factor. Gage factor is the dimensionless ratio of the ratio of the gage resistance in response to the strain divided by the strain ratio.
Typically, metal foil-type resistance strain gages have a gage factor of 2. However, where a high gage factor on the order of 4 is desired to provide appropriate gage sensitivity for driving a signal-generating circuit, it has been found that metal foil formed of exotic materials such as an alloy of Platinum and Tungsten provides the desired high gage factor.
Heretofore, Platinum-Tungsten (PtW) foil gages have been manufactured by ion beam milling, which required substantial investment for the ion beam milling machine. Furthermore, difficulties have been experienced in establishing process controls to provide the desired gage configuration with this process.
Thus it has been desired to find a way or means of fabricating high gage factor electrical resistance strain gages in a simple low-cost manner which produces reliable and accurate strain indication.